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Author Topic: Ladder fed dipole up, thanks.  (Read 16292 times)
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Superhet66
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« on: June 29, 2010, 11:19:11 AM »

I'm a happy camper.

I only had the weekends this past month but the ladder fed, 135' ft. dipole is up at 50' in the air. Unbroken runs from the posterior of the J. Matchbox to the far ends.

A flat, level, 90' Horiz. run and two 22.5' drops on either end with a center supported pulley at the split.
#10 pvc stranded wire. The ladder is 1/2" pvc pipe w/ 6" separation.

The thing is not as heavy as it sounds. It hoisted up nicely and HD nylon masons string is taking the load off the center > ( a nice vintage Johnson spreader )

It was WORK getting this damn thing up and happy in the trees alone.
A few ( quite a few ) stupid moves cost me time but resulted in other ideas that should keep this thing in the air a while.

My only panic moment was forgetting the internal relay in the match box ( duh ).
I was getting just enough bleed to tease me. Once I threw the relay over, Bing, nice fat signals  Wink

The Match box has been a shelf queen up to this point and I love it in use.
Broad, flat, repeatable tuning with ease. The MFJ will be a back up only now.
It's a whole new animal and I'm getting used to it. At 35 watts carrier I've been talking to who ever I hear with good reports  Smiley

So Thanks!
for all the input and info from the monster thread a few weeks ago, this is the pay off.

   ( "a Db here a Db there" ) Thanks Mr VU!
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WA1GFZ
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« Reply #1 on: June 29, 2010, 03:25:23 PM »

Replace the string ASAP it won't last long or it will dig itself in and won't come down until it breaks.
BTW I modeled the dipole with vertical drops vs the KB3AHE antenna and found the vertical drops give you a cloud burner radiation pattern compared to Frank's configuration.
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K5UJ
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« Reply #2 on: June 29, 2010, 04:08:22 PM »

Superh, good deal--i have almost exactly the same antenna also on Tom and HUZ recommendation.   I was amazed at the difference on 75 m. between having it at 50 feet v. my earlier 1 wave length loop at 30 feet.  That 20 foot higher dipole added several dB.  If it is a cloud burner I don't mind in my case because I also have a 1/4 w. vertical on 75.   But I'm curious as to what Frank's configuration is.  I can't remember it.

Rob 
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K3ZS
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« Reply #3 on: June 29, 2010, 04:09:23 PM »

Today I did the same thing.    The ladder line fed 135 dipole I have has been up about 12 years.    This week a dead tree fell over and hit the dead tree where one end of the antenna was tied.   The tree guys came today and I got the end of the antenna even higher in another live tree.    I use double braided dacron that you can obtain from many of the antenna supply places.    The dacron that has been up under tension for 12 years still is good, some that has been hanked up had the outer layer eaten by animals or birds.    Dacron or dacron shielded Kevlar is the only thing to use for antenna rope.    Nylon or polypropolene (I can't spell it right) will deteriorate in the sun.   Try DX Engineering, RadioWare ,  Radio Works or Wireman web sites for this rope.  I have never found any at the hardware or home improvement stores.
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Superhet66
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« Reply #4 on: June 29, 2010, 04:12:14 PM »

Well,

Next weekend I'll set up pulleys & jacketed steel wire I bought a while ago. I'll look into Dacron or dacron shielded Kevlar also as it's less hassle to work with.

One of the mistakes I mentioned was pulling on rope that had been up a while and "pop" I lost a couple hours re-shooting the tree.

As to the skyburner behavior with the vertical component I guess it remains to be seen. I am curious also as to what configuration KB3AHE has.
                          

I'll follow up with pics. It's tough to take pictures of mostly nothing. Dusk/dawn seems best. ( I have to stare at the thing every time I step off the porch... ; Smiley 

                  Thanks guys,            
                                                              DJ

                                                                    
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The Slab Bacon
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« Reply #5 on: June 30, 2010, 07:52:25 AM »

model away! Sometimes ya just gotta do what ya gotta do!

It was a lot cheaper to build a shortened antenner than to buy a new house!!

* short ant.pdf (483.04 KB - downloaded 235 times.)
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K5UJ
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« Reply #6 on: June 30, 2010, 08:59:42 AM »

Replace the string ASAP it won't last long or it will dig itself in and won't come down until it breaks.
BTW I modeled the dipole with vertical drops vs the KB3AHE antenna and found the vertical drops give you a cloud burner radiation pattern compared to Frank's configuration.

I'm just curious how Frank's folded dipole at the same height (50 feet) is not a cloud burner.  I'm not getting how it has a lower angle--I'd think ground proximity would affect it just as much.
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ka3zlr
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« Reply #7 on: June 30, 2010, 09:27:15 AM »

Well done OM got yer anteener up Kewell Grin

73

Jack.
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KC2YOI
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« Reply #8 on: June 30, 2010, 10:08:13 AM »

Could someone model the ant. I just put up but with the 22.5' legs at a 45deg. angle and still in line with the 90' run? ( sloper style ) I have the room and I'm curious.

I left the legs as I hope to eventualy have the room for a full stretch. The idea was not shot down last time I brought it up so I went for it. A someone mentioned, I can always just zip it back against itself for an the effect of a straight 90'.

Thanks for the Dacron/Carbn fbr. sources Bob, I'm looking into it.

I copied the PDF of the folded dipole Mr. Slab. I could sneek that up perpendicular to the one I have for East West exposure. ( I hope it's not copyrighted... )  Cool

    Again,  If some could model what I described at the top but with the 45deg slopes it might be interesting....
                                                 D.

PS: The Tuna on the FT101 is a temp set up. It will be parked on a shelf where the twins come in....


* Johnson ladder..jpg (19.67 KB, 293x240 - viewed 483 times.)
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w3jn
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« Reply #9 on: June 30, 2010, 10:43:44 AM »

N3DRB was running a very similar setup - barefoot FT-101 into a Flashbox and a 130' flat top up 40' or so.  Even so it was seldom he wasn't the Channel Master.

Indeed, Master Vu is right on - a dB here, a dB there, and pretty soon yer talkin' real money!
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Steve - WB3HUZ
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« Reply #10 on: June 30, 2010, 11:00:19 AM »

Both will be cloud burners and have identically shaped pattern when modeled at the same height. TNSTAAFL.

Keep what you got. I don't see how a shorter sloping antenna is going to be any better.



Replace the string ASAP it won't last long or it will dig itself in and won't come down until it breaks.
BTW I modeled the dipole with vertical drops vs the KB3AHE antenna and found the vertical drops give you a cloud burner radiation pattern compared to Frank's configuration.

I'm just curious how Frank's folded dipole at the same height (50 feet) is not a cloud burner.  I'm not getting how it has a lower angle--I'd think ground proximity would affect it just as much.
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W2VW
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« Reply #11 on: June 30, 2010, 11:06:32 AM »

Derb only gets out that well 'cause he's grounded to a corn still.

N3DRB was running a very similar setup - barefoot FT-101 into a Flashbox and a 130' flat top up 40' or so.  Even so it was seldom he wasn't the Channel Master.

Indeed, Master Vu is right on - a dB here, a dB there, and pretty soon yer talkin' real money!
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KC2YOI
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« Reply #12 on: June 30, 2010, 11:09:04 AM »

Thanks Steve, I'm not sure if you were referenceing my thought on the drops as far as shorter and sloped.
In the scenario I had in mind, the overall lenght would remain the same I would just bring the dropped ends out at a 45 in line with the level 90' run, the total would remain 135. I might have misunderstood also. Danka.

I need to get comfortable with illustrating and posting with PDF link, it saves a lot of typing  Wink

--------------------------------------------------------------------------------
"Flahbox", I wish I had the juice to flash it over!  Smiley

Speaking of the J. tuna,
Is anyone familier with the J. Matchbox mod that lifts all / most of the components off ground?

It was in a QRZ thread and they mentioned the Cebik  ( W4RNL ) Antennas Website.

I just registered with the site and have not found reference yet.

If I find it first I'll post it, if anyone knows what the heck I'm talking about or if it's all hooey, lemme know.....  

                                                    D

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K1JJ
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« Reply #13 on: June 30, 2010, 11:54:39 AM »

DJ,

Yes, as the Huzman said, the 90' flat top with the 20' dropped ends are fine.  It's almost like a cross between an inverted V and a dipole, but better. Heck, the Moxon beam uses a similar technique for both its driven el and ref and kicks ass. (But els are folded in horizontally)  

Of course, a full flat 130' flattop is best, but 90' of horizontal run is quite a good compromise. The lower losses of having the dropped ends vs: a 90' dipole with no dropped ends are a good step too.

At this point, the biggest effect on pattern of any of these antennas will be height above ground of the flat tops. Height will change things dramatically on 75M whereas simple changes in the flat top vs: dropped ends ratios will have little effect.  The average height of the array (when sloping like an inv vee) usually matters for take-off angle. With the dropped ends, this "average height" rule appears to be violated to some degree, which is a good thing for your antenna config.

Stick with what you have. Pulling the dropped ends out as far as possible will also help. That antenna will make a new world for you on 75M - just wait til the fall and winter condix roll in... on certain nights you'll be working the west coast on just 35 watts Wink

(Been busy trying to get some sailing in on the CT River wid Yaz.)

T
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KC2YOI
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« Reply #14 on: June 30, 2010, 12:19:55 PM »

OK, that works for me,  Talk time will be the puddin and proof.

The next step is a more permanent anchor point for the feed and lightning suppression.

I poured over the threads here re: grounding / lightning / bleeding etc. and I have a pretty good idea of the material & designs I might use.
I'll throw it to the lions before I break out the sakrete and hole saws.

Also, as of now, I'll break the ladder line drop @ 7ft., just after the suppresion stuff at close to a 90* angle toward the shack, tie in to the house and still allow for drop and sway in the trees with what I have planned.

I'm stuck away from the house this week with work.  Sad
After all the hullabaloo getting this baby up I had 45 fast fargkin minutes to load up, grab a few contacts, throw the spaghetti out the window to ground and hit the road for 150 mi.
Friday can't get here fast enough.  I'ze been bit docta....


* Dipole w 45deg drops.JPG (7.2 KB, 650x296 - viewed 459 times.)
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WA1GFZ
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« Reply #15 on: June 30, 2010, 12:43:27 PM »

I found Frank's design had less signal at 90 degrees. Yes both are high angle antennas.
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« Reply #16 on: June 30, 2010, 07:01:24 PM »

I found Frank's design had less signal at 90 degrees. Yes both are high angle antennas.

Okay Frank thanks; I understand now.  I'm always interested in improvements I can try. 
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WA1GFZ
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« Reply #17 on: June 30, 2010, 09:13:09 PM »

I have a similar problem at other QTH and did a lot of modeling frank's antenna seems the best. My lot is 175 feet but 115 between the two tallest tree tops
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KB2WIG
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« Reply #18 on: June 30, 2010, 10:44:14 PM »

If yer gunna use sakrete, throw in a #2 shovel full of portland per bag of the stuff...  mix 'er up dry, then add the water to the mix. Measure the amount of water per the bag instructions, and thoroughly mix 'er up.  (err on the side of less water) Pour, cover, keep moist fer a few weeks before adding a 'load' to it.

Mudwerk lasts a long time.

klc
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ke7trp
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« Reply #19 on: July 01, 2010, 01:29:29 AM »

This is what I have been using for the last couple years.  Once I got the feedline length right, All bands on the KW matchbox tuned in nicely.  I have talked to most people on this board from the west coast with it.  I wish I had it a bit higher but its good for now.

C
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KC2YOI
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« Reply #20 on: July 01, 2010, 08:58:21 AM »

Frank, I'm going to build the KB3AHE and pull it up broad side to East / West.
It will just fit, it gives me an excuse to build something and it should be cool to stare at with my morning coffee. I might be able to get it up over 65' in the spot I have.

Klc, thanks for the mud advice. It's for a 4x4 that will be the break point for the 90* turn in the feed and hold the bleed / phaser / ground shunt frankestein sw.

C,  I've only loaded the set up on 75m, this Friday I'll put the set up thru its paces accross the bands and report back to the "mother ship" (To quote Bear).
                                                            
                                                                        Thanks, DJ

                                                          
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ka3zlr
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« Reply #21 on: July 01, 2010, 09:23:55 AM »

Hello,

 On Huz'ez Web Site there's an interesting antenna article an it werks well. Smiley

http://www.amwindow.org/tech/htm/160smallants.htm

73

Jack.

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ke7trp
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« Reply #22 on: July 01, 2010, 11:33:58 AM »

If you use the KW matchbox,  Sit down and make a chart of loading for each band.  If you mis a band and cant tune it, Its like due to the feedline length.  I struggled with this for a while.  I ended up adding about 10 ft of feedline outside. Once I got the right length, all bands fell into the tuning range.  In fact, 80 and 40 need very little change in the dials which is nice.  The top bands are also close to the same dial positions. 

This antenna and tuner actualy works damn good on 40 and 20.  I use it on 20 meter SSB or AM and have made thousands of big signal contacts with it. I talked to the azores on 15 meters with it first call.  Recently, I have been on 20 meters late at night rag chewing with the guys in australia on AM putting 50 to 60 DB out there with it.

C
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KC2YOI
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« Reply #23 on: July 01, 2010, 01:01:32 PM »

I built quite a bit of extra length into the feed for tuna-bility.
I'll chart the findings clearly and see what the gang here thinks.

I find getting used to a new rig/tuna/feed/ant. the most interesting, frustrating, rewarding and at times nerve wracking part of it all.

I'm a bit nervous about kids being kids and seeing my ladder line as.... a LADDER!  Shocked . I've taken this into consideration (7' up ) but I still think about some of the screwy stuff I did as a kid, phew.

                                                Is it Friday yet?   D
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« Reply #24 on: July 01, 2010, 01:11:39 PM »

I had to make mine dog proof.. I used 2X4s bolted to the eve to support the line. 

Also.. Consider putting in some Static coils on your antenna.  These made a big difference for me and they dont effect the tuning at all.  You can make your own or buy some premade coils from DX engineering.  I mounted mine in a waterproof box outside the house. The coils tie to a Ground rod, then to each leg of the feedline. 

Before I had these, I could hear and see the static discharge from the back of the KW to the case with a loud POP. The RX no longer had that big pop and a moment before the noise came back. 

Something to consider...

Clark



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